Guide: how to choose your water filter?

There are many portable water filters out there for drinking and cooking uses (and secondarily for brushing teeth…). You won’t find the sole and ultimate filtration solution but rather a system that will meet specific needs. The filter can be used separately or in combination with other elements like chemical purification tablets or pre filters.

Determine your needs

After giving them some thought, simply answer the following questions. Your first input may outline the style of filtration system that you really need.

Where do you intend using your filtration system ?

You won’t be using the same water filter if you are always outdoors on the road, if you go bivying, camping, or if you stay indoors at home, or if you are driving, biking… Some models are compactly designed and lightweight while others have a design and performance suitable for a more stationary use. That’s the case of the Base camp Pro filter by Katadyn which, as the name indicates, is recommended for base camps. The place you are in will have a significant influence on the type of water filter you pick. In countries at risk, your water filter should be more efficient and a chemical treatment should be a must. At high altitude, there may be less hydrocarbons found in water than in urban/peri-urban areas. In rural areas, water sources can be polluted with dead animals or chemical treatments resulting from agricultural activity…

The place of use should pin down the following specs:

volume and filtration capacity
filtration performance
combination of water filtration systems

Who will be using the filtration system ?

If you are a large group, you should opt for a high-volume gravity filter. If you are solo travelers or pairs, your pick should be quite different. A water bottle/filtering straw can be sufficient for emergency one-off uses, and the Befree filter is a great alternative. Obviously, sharing the same straw with friends is hardly an option and so for this kind of scenario, you could select a more suitable system like the MSR Guardian purifier. The type of activity will also influence the type of filter picked. People who do a lot of sport or trail runners will definitely prefer a lightweight minimalist system quick to operate like the MSR Trailshot water filter. If you go kayaking, you can bring a bulkier filter…

The number of users should pin down the following specs:

bulk and weight
volume and filtration capacity
design

What do I have to take into account ?

When choosing your water filtration system, first pay special attention to the following specifications :

filtration system (chemical, mechanical…)
technology (membrane, glass fiber, activated carbon…)
performance in micron
effectiveness (against bacteria, viruses, Protozoa, hydrocarbons…)
filtration capacity (from a few liters up to hundreds of thousands liters)

Different water filter technologies :

Membrane technology : Water under pressure is forced to pass through the microperforated part of the filter. Sawyer membranes like some other fiber membrane filters are self-cleaning and have a long useful life. Depending on the models, the filter removes most of the contaminants (up to 99,999%)
Glass fiber technology : Viruses excluded, this system captures most of the impurities found in water including chemicals. Pumping is easier with this technology but cleaning is impossible. Lifetime of glass fiber filters is shorter than lifetime of membrane filters. Katadyn uses this technology.
Hollow fiber technology : Almost identical to glass fibers, hollow fibers do not trap chemical products and do not improve the taste of water.
Activated carbon : it’s a commonly used technology that works better at filtering out chemical products and improving the taste of water. Activated carbon filters are not effective at removing protozoa, bacteria and viruses
Ceramic technology : Though ineffective on viruses, ceramic filters are among the most efficient filters on the market. Suitable for all types of water, including very turbid waters. Easy to clean. Their downside?, they are brittle. The ceramic cartridge could break if dropped. You won’t be able to use it anymore.

There are also UV filtration systems, ion exchange filters and of course chemicals (which are, by the way, the only water treatment on the market to be effective in removing viruses).

Filtration performance in micron :

The filters mentioned below can filter out pathogenic organisms of different sizes with a filtration performance expressed in micron :

one of the most efficient filtration systems there are, the Sawyer filter, provides a fiber technology featuring 0.1 µm filtration
Some filters filter out viruses by providing 0.02 µm filtration, and this is what the MSR Guardian purifier will do for you. It’s one of the most complete filtration systems on the market.
Katadyn fiber glass filters provide about 0.2 µm filtration, the same is true for some MSR filters like the Trailshot water filter
Some filtering straws like Lifestraw portable water filters also provide 0.2 µm filtration
Other models, like the Aquamira Frontier Pro, provide 2µm filtration and are far less effective.

For general information, take a look at the following pathogen size range :

1µ to 15µ in diameter: Amebic dysentery, giardia, lamblia, cryptosporidium, …
ranging from 0.2µ to 5µ in size : E-coli, salmonella, cholera, …
0.02µ to 0.2µ in size : Hepatitis A, Norwalk virus, rotavirus, poliovirus, …

Effectiveness :

No single filtration method can remove completely all viruses, bacteria, protozoa and chemicals (hydrocarbons, etc.). However, some models (ceramic or membrane filters for example) perform well. At any rate, the best advice to remember is to use a combined system of dual water purification: optimum mechanical filtration plus chemical filtration.

Filter capacity :

Featuring a self-cleaning technology, the Sawyer filter is leading the market in terms of filtration capacity with no less than 375,000 liters.
MSR guardian filters offer a filtration capacity limited to 10,000 liters
MSR Trailshot has a 2,000 liter filter capacity
The capacity of the filtering Lifestraw is up to 3,000 liters
The capacity of the Aquamira Frontier Pro doesn’t exceed the 100-liter mark
To extend filter life, some combined systems offer replacement filter elements, that’s what the Katadyn Combi is all about : you can replace the activated carbon cartridge. For this filter, the ceramic capacity is 50,000 liters while the activated carbon capacity is 400 liters.

As a second step, comfort can be another factor that may guide your decision:

filtration speed (oftentimes technology-based)
design (gravity, straw, mechanical…)

Beware, there is no magic remedy at rock-bottom price. Don’t play with your health especially when it concerns hydration and contamination, risks are too high. Make sure you err on the side of trusted brands such as Katadyn, MSR, Lifestraw, Sawyer, Micropur… Take a look at the products tested by many adventurers and outdoor enthusiasts and read their reviews posted on their blogs.

Need an example of water filter ?

" The two of us we’re heading for a long-distance 15-day hike in the mountains in total self-sufficiency. We are carrying our backpacking gear throughout our journey on the trail. We’re also carrying some water supplies that we will complete every day by choosing water sources along the trail for cooking, washing and mainly hydrating our bodies."

Place of use :

mountain hike
heavy use, several times a day
for use at bivouac

Frequency of use :

high
long trips
2 people

One of the best possible gear solutions suitable for this outdoor scenario :

When heading out in pairs, it’s important to pool your backpacking gear. Stove, pot, water filter, hygiene equipment and sleeping system (tent/tarp) bulk and weight must be shared according to the loading capabilities of each hiker. It is unnecessary to carry two stoves or two filters…

Mountains provide favorable conditions for fresh healthy water, so both hikers in our scenario can fill up, but downstream water pollution may ruin their collecting task : mountain streams or water sources can be contaminated by dead animals upstream for example. Traces of hydrocarbons are unlikely to be found unless they hike downstream of a high altitude station ǁmountain resort?ǁ (in that case, using a carbon filter like the Katadyn pump filters should be considered as a safe solution).

To summarize :

you need ten liters of filtered water per day
there is no hurry, plan ahead of time your filtered water needs before setting off (how much you will consume for the distance covered) then you filter out your water when you stop for bivouacking.
there are many natural water supplies with pristine water, free of hydrocarbons or chemicals

Optimized solutions :

the MSR Guardian Purifier is a tried and true choice. It is efficient and easy to use. It’s relatively lightweight and not bulky. It is compatible with Nalgene bottles and most of water bladders. With a flow rate of 2.5 L per minute, you can fill up your bottles quickly.
the Sawyer filtering straw is a good option for our hiking scenario. Although it has a lower flow rate compared to the Guardian and it is less suitable for an « advanced planning » filtration operation (recommended to filter out your water if needed), all in all the weight and size are two major advantages of this filtration system.

Besides using a mechanical filtration method, it is highly recommended that you add a tablet of Micropur Forte in your water. If you combine both methods you are sure to stay on the safe side.

Conclusion

Every need has its own filtration system, the solution being to find the right compromise. Owning the right water filter is not an end in itself, you also have to learn how to use it correctly.

To complete your water filtration gear, we recommend you read this article on Nalgene bottles and a selection of products dedicated to proper hydration.

Matthieu from NoPanic for Freezedried & Co